I don't think, based on these few statistics here, that you can say that Athiesm causes suicide. As many here have pointed out, correlation does not prove causation. It's even less significant when it comes to the impact of Atheism on a particular person.
There could be some risk factor that tilts a person both towards Atheims and depression. If you look at the map, you can see that suicide seems more common in areas further from the equator. Studies show that people have more depression in the winter, when the days are shorter. Possibly it is the lack of sunlight that causes people to be depressed, and that depression causes them to question the existence of God, and make them also more likely to commit suicide.
Most religions forbid suicide, so it could also be that some people depressed and unhappy, but avoid suicide because they fear eternal damnation
There also could be a genetic component. People in Africa and South America could have some genetic characteristics that pushes them more towards accepting the religion they grew up with and, at the same time makes them more likely to be happy and less prone to suicide. If you look at the US, it does not have as much depression as the northern European countries, which you might expect, since the US has a lot of people who descended from Northern European countries, but also from all over the world.
It's hard to say, these are just guesses, but really, all of this is irrelevant when it comes to one person, and that one person's chance for happiness. You can't just believe in God because it might make you a happier person, either you believe or don't believe, based on the facts. I would rather live in reality rather than delusion, even if that delusion might make me happier. As a JW, you might have enjoyed some parts of the experience, being part of a group and the social support that came with that, thinking you were doing important work, looking forward to a happy future. Now that you don't believe that you cannot just go back and pretend you believe, or at least I couldn't. Ignorance may be bliss, but I can't go back to ignorance.
My suggestion is to figure out what part of being a believer (other than thinking an invisible person exists) made you happy, and seek that in your new life. Find a cause you believe in and contribute towards that. Find a network of supportive friends. Work towards some goal, like an education, or a new skill. Those things will bring you happiness whether you believe in God or not.